JP3688274B2 - Paddy rice cultivation method to suppress cadmium absorption of paddy rice - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rice cultivation method for suppressing cadmium absorption of rice.
[0002]
[Prior art]
In paddy rice cultivation, prevention of absorption of heavy metals in soil, particularly cadmium, is eagerly desired from the viewpoint of preventing contamination of rice, and various methods have been tried. For example, there is a method of removing contaminated surface soil and removing uncontaminated soil (Non-patent Document 1). However, in addition to the huge cost of the land, the effect is temporary if the lower layer is contaminated, and disposal of the removed contaminated soil becomes a problem. In addition, there is a method for suppressing cadmium absorption by introducing alkaline material such as calcium (for example, Patent Document 1). However, this method requires a large amount of 5 to 10 tons per 1 ha in order to exhibit the effect, so that the workability is poor, and the organic nitrogen in the soil is easily mineralized by the multiple throwing of alkaline materials. There is a risk of paddy rice lodging.
[0003]
[Non-Patent Document 1]
Act on Prevention of Soil Contamination of Agricultural Land (Act No. 139 of December 25, 1945)
[Patent Document 1]
Japanese Patent Laid-Open No. 10-98955
[Problems to be solved by the invention]
An object of the present invention is to provide a paddy rice cultivation method capable of suppressing cadmium absorption of paddy rice and preventing lodging of the paddy rice within the range of normal cultivation management.
[0005]
[Means for Solving the Problems]
That is, according to the present invention, 40 to 240 kg of CaCN ₂ containing material as CaCN ₂ , 100 to 400 kg of SiO ₂ containing material as SiO ₂ , 100 to 400 kg of CaO containing material as CaO, and 40 mg of MgO containing material as MgO per ha. This is a paddy rice cultivation method in which ˜180 kg, P ₂ O ₅ containing material is P ₂ O ₅ and 16-80 kg is applied from the autumn rice harvesting to before spring rice transplanting. In this case, the CaCN ₂ -containing material is lime nitrogen, and the SiO ₂ , CaO, MgO and P ₂ O ₅ containing material has a molar ratio of (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) of 1.2 to It is preferable that the inorganic composition is 2.5, and it is particularly preferable that the elution rate of SiO ₂ in a 4% by mass citrate buffer solution (pH is 5.5) of the inorganic composition is 50% or more. Furthermore, this inorganic composition is more preferably an inorganic composition obtained by heating, melting and cooling raw material powder containing SiO ₂ , CaO, MgO, and P ₂ O ₅ .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention shall be CaCN ₂ to reduce the rice cadmium content by suppressing cadmium absorption of rice, high SiO ₂ content substance dissolution property to prevent the lodging of rice at pH5 or higher pH range In other words, the present inventors have found that a CaO-containing material and a MgO-containing material can further increase the reduction of cadmium content in rice.
[0007]
In the present invention, the CaCN ₂ containing material, the SiO ₂ containing material, the CaO containing material, the MgO containing material, and the P ₂ O ₅ containing material are in the period from autumn rice harvesting to before spring paddy rice transplantation, It is applied once or divided into several times. Other than this period, for example, about 1 month before heading or application as additional fertilizer such as ear manure, it becomes possible to suppress cadmium absorption of paddy rice, but CaCN ₂ comes into contact with paddy rice and causes growth failure and lodging of rice paddy. There is a risk of incurring, and it becomes difficult to cultivate paddy rice within the range of normal cultivation management. Particularly preferably, it is applied at the time of rice wake after autumn rice harvesting or rice wake before spring. In this case, the application may be either batch charging or split charging, and it is preferable to use the materials after mixing them. Furthermore, it is desirable to fill the water after application with water.
[0008]
In the present invention, 40 to 240 kg of CaCN ₂ containing material is applied per 1 ha as CaCN ₂ . If it is less than 40 kg, the effect of suppressing cadmium absorption is insufficient, and if it exceeds 240 kg, the effect of suppressing further cadmium absorption is not observed, and excessive rice nitrogen causes lodging and adversely affects yield and quality. The fear increases. 80 to 180 kg per 1 ha is a preferable range. As CaCN ₂ -containing substances, lime nitrogen, especially CaCN ₂ Lime nitrogen having a guaranteed content of 55% or more is preferred.
[0009]
In addition, in the present invention, 100 to 400 kg of SiO ₂ containing material as SiO ₂ , 100 to 400 kg of CaO containing material as CaO, 40 to 180 kg of MgO containing material as MgO, and P ₂ O ₅ containing material P per ha. Apply 16-80 kg as ₂ O ₅ . When the application rate of the SiO ₂ -containing material is less than 100 kg as SiO ₂ per ha, the effect of further suppressing cadmium absorption and the effect of preventing the lodging of paddy rice is insufficient, and when it exceeds 400 kg, a further effect is recognized. It becomes impossible. 150 to 240 kg is a preferred range. Both CaO and MgO are alkaline components, but if the application rate of the CaO-containing substance is less than 100 kg as CaO per ha, or the MgO-containing substance is less than 40 kg as MgO per ha, the effect of suppressing cadmium absorption Is no longer allowed. If it exceeds 400 kg as CaO or 180 kg as MgO, the quantitative balance between the acidic component (SiO ₂ and P ₂ O ₅ ) and the alkali component to be applied may be lost, leading to a decrease in SiO ₂ elution rate, There is a possibility that the effect of SiO ₂ may be hindered. P ₂ O ₅ is a component necessary for ensuring the SiO ₂ elution rate, and when the application amount of the P ₂ O ₅ -containing material is less than 16 kg of P ₂ O ₅ or more than 80 kg per ha, the acid to be applied is also applied. There is a risk that the quantitative balance between the component and the alkali component is lost, and the elution rate of SiO ₂ cannot be secured.
[0010]
In particular, the SiO ₂ -containing material, CaO-containing material, MgO-containing material, and P ₂ O ₅ -containing material have a molar ratio of (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) of 1.2 to 2.5. By adjusting and applying so that there is, there is an advantage of increasing the SiO ₂ elution rate. In addition, the SiO ₂ -containing material, the CaO-containing material, and the MgO-containing material in such a ratio that the elution rate of SiO ₂ in 4 wt% citrate buffer (initial value of pH is 5.5) is 50% or more. Further, by adjusting and applying the P ₂ O ₅ -containing substance, a further effect of suppressing cadmium absorption and an effect of preventing lodging of paddy rice can be obtained.
[0011]
Here, the SiO ₂ elution rate includes the amount of SiO ₂ eluted in the citrate buffer solution in the SiO ₂ -containing material, the CaO-containing material, the MgO-containing material, and the P ₂ O ₅ -containing material. Expressed as a percentage of the total SiO ₂ content. The measuring method is that about 100 g of a sample is pulverized with a vibration mill to make a sieve with an opening of 150 microns, about 1 g is precisely weighed, and a 2N sodium hydroxide aqueous solution is added to a citric acid aqueous solution to adjust the pH to 5.5. Add 150 ml of adjusted 4 mass% sodium citrate buffer, shake in a 30 ° C. water bath for 1 hour, filter the resulting solution with filter paper, dilute the filtrate with pure water, and then be contained in the filter paper The amount of SiO _{2 is} measured by ICP (inductively coupled plasma optical emission spectrometry).
[0012]
The present invention relates to an inorganic raw material powder containing SiO ₂ , CaO, MgO, P ₂ O ₅ as components, such as phosphate rock, serpentine, silica, limestone, ferronickel ore, silicomanganese ore, various blast furnaces, phosphorus slag, It is preferable that it is an inorganic composition obtained by combining fly ash, sludge incineration ash and the like so as to have the above molar ratio, and heating and melting and cooling them. For heating and melting, an external heating electric furnace, an arc furnace, a high-frequency heating furnace or the like that can be melted at 1350 ° C. or higher can be used. The cooling of the melt is preferably rapid cooling by blowing compressed air or water from the viewpoint of SiO ₂ elution rate.
[0013]
When the material according to the present invention is applied to rice fields, it can be used in combination with commonly used fertilizers such as urea, ammonium sulfate, ammonium chloride, ammonium phosphate, lime superphosphate and potassium chloride. In particular, when applying nitrogenous fertilizer as a basic fertilizer, the material according to the present invention can be applied without adjusting the amount of nitrogenous fertilizer within the range of normal cultivation management.
[0014]
【Example】
Hereinafter, the present invention will be described in more detail based on examples and comparative examples.
[0015]
Example 1
Lime nitrogen (trade name “granular lime nitrogen” manufactured by Denki Kagaku Kogyo Co., Ltd.) was prepared as a CaCN ₂ -containing substance. This has a CaCN ₂ content of 55% by mass, carbon of 21% by mass, calcium oxide of 23% by mass, and a particle size of 0.5 to 4.0 mm. On the other hand, as an inorganic composition containing a SiO ₂ -containing material, a CaO-containing material, an MgO-containing material, and a P ₂ O ₅ -containing material, silica, serpentine, quicklime, and phosphate rock are made of SiO ₂ , CaO, MgO, P ₂ O ₅ is mixed so that each contains 36% by mass, 37% by mass, 16% by mass, and 6% by mass, and the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) is 1.7, After being melted by heating to about 1400 ° C., water is sprayed and rapidly cooled, the same composition as the raw material composition, particle size of 0.3 to 1.0 mm, 4 mass% citrate buffer (the initial value of pH is 5. A material having a SiO ₂ elution rate of 95% to 5) was produced.
[0016]
The cultivation management of paddy rice is sprayed with 200 kg and 600 kg of lime nitrogen and the inorganic composition per 1 ha, respectively, in a rice field of fine-gray lowland soil (0.1 M HCl soluble cadmium content 0.40 mg / kg dry soil). did. This corresponds to 110 kg of CaCN ₂ , 216 kg of SiO ₂ , 222 kg of CaO, 96 kg of MgO, and 36 kg of P ₂ O ₅ . Further, superphosphate lime fertilizer and potassium chloride fertilizer were sprayed at 200 kg and 56 kg, respectively, per ha. Then, after watering and submerging, transplanting paddy rice (Koshihikari), it was always submerged until one month before harvesting, and the other was subjected to customary cultivation management and the above-ground part was harvested.
[0017]
The cadmium content of rice is expressed as an index when the cadmium content in brown rice is analyzed by nitric acid decomposition-ICP method, and the cadmium content in brown rice is 100 when the above inorganic composition alone is not applied. did. As a result, the cadmium content of brown rice was 0.06 mg / kg, and the index was 32. Moreover, the lodging of rice was evaluated by measuring the angle of the stem from the ground part at the time of cutting. That is, the smaller the lodging, the closer to the right angle (90 °), and 0 ° when completely lying down. As a result, it was 70 °.
[0018]
Example 2
Paddy rice cultivation was carried out in the same manner as in Example 1 except that the application amount of lime nitrogen was 100 kg per ha (that is, 55 kg as CaCN ₂ ). As a result, the cadmium content of brown rice was 0.10 mg / kg, the index was 53, and the lodging was 70 °.
[0019]
Example 3
Paddy rice cultivation was carried out in the same manner as in Example 1 except that the application amount of lime nitrogen was 400 kg per ha (that is, 220 kg as CaCN ₂ ). As a result, the cadmium content of the brown rice was 0.05 mg / kg, the index was 26, and the lodging was 50 °.
[0020]
Example 4
Rice cultivation was carried out in the same manner as in Example 1 except that the application amount of the inorganic composition was 300 kg per ha (that is, 108 kg as SiO ₂ , 111 kg as CaO, 48 kg as MgO, and 18 kg as P ₂ O ₅ ). As a result, the cadmium content of brown rice was 0.08 mg / kg, the index was 42, and the lodging was 50 °.
[0021]
Example 5
Paddy rice cultivation was carried out in the same manner as in Example 1 except that the application amount of the inorganic composition was 1000 kg per ha (that is, 360 kg as SiO ₂ , 370 kg as CaO, 160 kg as MgO, and 60 kg as P ₂ O ₅ ). As a result, the cadmium content of the brown rice was 0.06 mg / kg, the index was 32, and the lodging was 70 °.
[0022]
Example 6
Paddy rice cultivation was carried out in the same manner as in Example 1 except that 200 kg of ammonium sulfate as the basic fertilizer was sprayed together with lime superphosphate fertilizer and potassium chloride fertilizer when lime nitrogen was sprayed. As a result, the cadmium content of brown rice was 0.07 mg / kg, the index was 37, and the lodging was 50 °.
[0023]
Comparative Example 1
Paddy rice cultivation was carried out in the same manner as in Example 1 except that lime nitrogen was not sprayed. As a result, the growth was poor at the early panicle formation period (about 2 months after rice transplantation), and the cultivation was stopped.
[0024]
Comparative Example 2
Paddy rice cultivation was carried out in the same manner as in Example 1 except that ammonium sulfate was sprayed in place of lime nitrogen and a nitrogen equivalent equivalent to lime nitrogen was sprayed. As a result, the cadmium content of brown rice was 0.17 mg / kg, the index was 89, and the lodging was 70 °.
[0025]
Comparative Example 3
Paddy rice cultivation was carried out in the same manner as in Comparative Example 2 except that the inorganic composition was not sprayed. As a result, the cadmium content of brown rice was 0.19 mg / kg, the index was 100, and the lodging was 30 °.
[0026]
Comparative Example 4
Paddy rice cultivation was carried out in the same manner as in Example 1 except that lime nitrogen was not sprayed. As a result, the cadmium content of brown rice was 0.10 mg / kg, the index was 53, and the lodging was 30 °.
[0027]
Example 7
As an inorganic composition, SiO ₂ , CaO, MgO and P ₂ O ₅ contain 41% by mass, 31% by mass, 16% by mass and 6% by mass, respectively, and the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) Is 1.3, and an inorganic composition having an SiO ₂ elution rate of 85% in a 4% by mass citrate buffer (pH is 5.5) is 246 kg as SiO _{2 and} 186 kg as CaO. Rice cultivation was conducted in the same manner as in Example 1 except that 96 kg as MgO and 36 kg as P ₂ O ₅ were applied. As a result, the cadmium content of the brown rice was 0.06 mg / kg, the index was 32, and the lodging was 58 °.
[0028]
Example 8
As an inorganic composition, SiO ₂ , CaO, MgO and P ₂ O ₅ contain 30% by mass, 43% by mass, 16% by mass and 6% by mass, respectively, and the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) Is 2.2, an inorganic composition having a SiO ₂ elution rate of 90% in a 4% by mass citrate buffer (initial value of pH 5.5) is 180 kg as SiO _{2 and} 258 kg as CaO. Rice cultivation was conducted in the same manner as in Example 1 except that 96 kg as MgO and 36 kg as P ₂ O ₅ were applied. As a result, the cadmium content of the brown rice was 0.06 mg / kg, the index was 32, and the lodging was 63 °.
[0029]
Comparative Example 5
As an inorganic composition, SiO ₂ , CaO, MgO, and P ₂ O ₅ contain 36% by mass, 23% by mass, 16% by mass, and 20% by mass, respectively, and the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) Is 1.0, and an inorganic composition having a SiO ₂ elution rate of 48% in 4% by mass of citrate buffer (pH is 5.5), 216 kg as SiO _{2 and} 138 kg as CaO Rice cultivation was conducted in the same manner as in Example 1 except that 96 kg as MgO and 120 kg as P ₂ O ₅ were applied. The cadmium content of the rice was 0.10 mg / kg, the index was 53, and the lodging was 35 °.
[0030]
Example 9
Paddy rice cultivation was carried out in the same manner as in Example 1 except that intermittent flooding (falling water-intermittent drainage-intermediate drying-intermittent irrigation-intermittent water) was used instead of constant flooding until one month before harvesting. As a result, the cadmium content of brown rice was 0.07 mg / kg, the index was 32, and the lodging was 73 °.
[0031]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the paddy-rice cultivation method which can suppress the cadmium absorption of a paddy rice and can prevent the lodging of a paddy rice within the range of normal cultivation management is provided.

Claims (4)

Per 1ha, 40~180kg 40~240kg the CaCN ₂ containing material as CaCN _2, 100~400kg 100~400kg the SiO ₂ containing material as SiO _2, the CaO-containing material as CaO, MgO, containing substances as _{MgO, P} 2 O A paddy rice cultivation method characterized by applying 16 to 80 kg of ₅ containing substance as P ₂ O _{5 in} a period from after harvesting autumn rice to before spring rice transplanting. The CaCN ₂ -containing material is lime nitrogen, and the SiO ₂ , CaO, MgO and P ₂ O ₅ containing material has a molar ratio of (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) of 1.2 to 2.5. The method for cultivating paddy rice according to claim 1, which is an inorganic composition. Inorganic composition, 4 weight percent citrate buffer rice cultivation process according to claim 2, wherein the SiO ₂ dissolution rate to (pH 5.5) is an inorganic composition over 50%. Inorganic composition, SiO 2, _CaO, MgO, rice cultivation of the raw material powder containing P ₂ O _5, claim 2 or claim 3, wherein the inorganic composition obtained by heating and melting cooling Law.